The present invention relates to an electromagnetic torque sensor comprising an emission coil for generating a magnetic field in an object whose torque is to be determined, having at least two reception coils which receive a response signal which is induced in the object by the magnetic field of the emission coil.
A magnetoelastic torque sensor is based on the inverse magnetostrictive effect, that is to say the effect according to which ferromagnetic materials experience a change in the magnetic susceptibility if mechanical stresses occur. Since mechanical stresses are induced not only by tensile forces and compressive forces but also by torsion, the inverse magnetostrictive effect can be used to measure torque, for example to measure the torque on a shaft in a contactless fashion. If a magnetic field is induced in a ferromagnetic layer or a shaft, a response signal, which can be detected by the reception coils, is generated in the layer as a function of the stresses which occur. Since the response signal is influenced by the stresses occurring due to torsion in the ferromagnetic material and which are caused in turn by the torque, the torque of the shaft can be inferred from the response signal. The detected measurement signal is dependent on the distance of the torque sensor from the ferromagnetic layer and on the temperature of the ferromagnetic layer. The accuracy with which the torque can be determined from the response signal therefore depends, inter alia, on how well the torque sensor can be positioned with respect to the object of which the torque is to be determined.